header image doesn’t display properly if header text is turned off

I wanted the header text on my siteto have a line break, so that ‘California Current Ecosystem’ is on a line by itself, and the rest of the text is on the second line. Apparently, WordPress doesn’t allow this. I also wanted to incorporate a couple of logos on the left side of the banner, but the theme only allows one logo and puts it smack in the center of the banner.

I thought I’d get around that by creating a new banner image with the text and the logos incorporated into it, and turn off the ‘Display Site Title and Tagline’ option in the ‘Site Identity’ menu. I created the banner I wanted, and sized it to 1900×250 pixels, as the theme suggests. However, when I uploaded the new banner and turned off the title text, the site only displayed a small portion of the full banner. If I turn the title text back on, it still displays only a portion of the banner, though slightly larger than before. What do I need to do in order to get the new banner to display properly with the title and tagline text turned off?

The page I need help with: [log in to see the link]